In the management of certain injuries to the lower extremities such as fractures of the tibia and fibula, malleolar fractures, or severe ankle sprains, it is common to completely immobilize the lower extremity by use of the well-known molded plaster or resin cast.
Once the injured extremity has become stable however, it has been found that recovery may be effected more rapidly by gradually and progressively permitting the extremity to bear weight and undergo other permitted exercises. Thus, for example, an orthopedic brace such as those disclosed in U.S. Pat. Nos. 4,280,489 and 5,125,400, both of which are assigned to the assignee herein and incorporated herein by reference in their entirety, may be utilized. These braces are pneumatic braces featuring one or more rigid outer shell members having associated therewith an inflatable liner or air cell for engaging a body part or limb. Commercial embodiments of the pneumatic brace incorporating the inventions disclosed in these prior patents are adapted to be fixed about the lower leg and typically comprise an outer shell member, or sidewall, in the form of a U-shaped stirrup having inflatable liners or air cells disposed within the stirrup member in co-extensive relation to the upstanding sidewalls thereof. Strap fastening means maintain the member sidewalls in engagement with confronting portions of the lower leg whereby each air cell serves as a firm supporting cushion of pressurized air between the irregular contours of the lower leg and the member sidewalls.
This brace construction is capable of stabilizing the ankle against eversion and inversion while permitting dorsiflexion and plantarflexion and while being worn inside a conventional shoe. Thus ambulatory functionality and permitted exercises are feasible thereby encouraging more rapid recovery from various injuries to the lower extremity, such as ankle sprains, than otherwise would be possible. The braces are used for ankle management in many countries because of their effectiveness, comfort and convenience in mobilizing yet protecting the ankle from re-injury. They have made "functional management" practicable.
The most common ankle injury is a sprain of the anterior talofibular ligament (ATFL) at the anterior margin of the lateral malleolus where swelling and edema originates. Since the ATFL is in the anterior front portion of the ankle, it lies in the uncovered area between the two sides of the stirrup member. To compensate for this uncovered area, many practitioners use a supplemental compression wrap during the initial few days after injury. An elastic ankle wrap is used just for this purpose.
Thus the recovery rate for ankle function following an inversion sprain may be related to the effectiveness of edema control at the injury site. Numerous authors have reported the use of a U-shaped felt or foam rubber device beneath an elastic wrap or adhesive tape for applying focal compression to the soft tissues adjacent to the fibular malleolus. See, for example, Wilkerson et al., "Treatment of the Inversion Ankle Sprain: Comparison of Different Modes of Compression and Cryo Therapy", JOSPT, Volume 17, No. 5, May 1993, pages 240-246. Focal compression consists of pressure application to surface concavities while adjacent proximal convex bony prominences are left uncompressed. See Wilkerson, "Treatment of the Inversion Ankle Sprain through Synchronous Application of Focal Compression and Cold", ATHLETIC TRAINING, JNATA, Volume 26, Fall 1991, pages 220-237. One of the objectives of the studies, as set forth in these articles, was to add focal compression to the uncovered area between the two sides of the stirrup with a pathway up the center of the stirrup for drainage of edema from the area of high pressure to the area of low pressure. Another objective was to add cryotherapy. The study shows that return to function by the patient is indeed faster with both focal compression and cold. But adding the cold temperature to the focal compression produced no better results than applying the focal compression at room temperature. This infers that focal compression accelerates healing but cold does not.
The problem with the prior art devices using a supplemental compression wrap under the stirrup is the inconvenience, bulk, and cost. Further it is an extra element to teach, handle and, maybe, misuse.